Association between Body Mass Index (BMI) and fraction of exhaled nitric oxide (FeNO) levels in the National Health and Nutrition Examination Survey (NHANES) 2007-2010

Psychological Stress and its relationship to Periodontal flora and salivary Nitrite/Nitrate

OBJECTIVE

Psychological stress can be a common risk factor for the development of oral and systemic disease; therefore, analysis of a pathophysiologic mechanisms that may explain this association may be significant in planning preventive strategies. The aim of this study was to investigate the association amongst academic stress, periodontal health, and salivary cortisol and nitrite and nitrate levels in a sample of university students.

METHODS

Participants (N = 14) were classified into 2 groups according to their exposure to academic stress due to periods of university exams (n = 6 and n = 8, respectively). All participants were subjected evlauted for their behavioural, psychological, and anthropometric parameters, as well as an oral health examination. A real-time polymerase chain reaction analysis in samples of saliva and plaque was used to detect Prevotella intermedia and Veillonella dispar as well as the total bacterial count. Nitrite/nitrate ratio (NR ratio) and cortisol in saliva were evaluated by enzyme-linked immunosorbent assay.

RESULTS

Full Mouth Bleeding Score, Full Mouth Plaque Score, and Gingival Index were significantly higher in the group exposed to academic stress. Nitrite was directly related to the presence of V dispar (coefficient, 0.13; P = .00; CI, 0.07 to 0.19) and inversely related to total bacterial count (coefficient, -0.07; P = .012; CI, -0.13 to 0.02). NR ratio was directly related to V dispar (coefficient, 4.35; P = .010; 95% CI, 1.35 to 7.36) and inversely related to total bacterial count (coefficient, -4.05; P = .018; 95% CI, -7.32 to 0.86).

CONCLUSIONS

These results confirm the importance of stress on periodontal health and salivary nitrite concentration and highlight a potential differential role of specific bacteria on nitrite concentration in saliva.

Can the Chinese study on the normal range of FeNO in children evaluate standardized asthma treatment efficacy in 6- to 12-year-old children?

Objective

By examining fractional exhaled nitric oxide (FeNO) levels and performing pulmonary function testing, this study explored whether the multicenter study on the normal range of FeNO in children in China can be used to evaluate standardized treatment efficacy in 6- to 12-year-old children with asthma.

Methods

A total of 115 children aged 6-12 years old who were first diagnosed with asthma and received standardized asthma treatment from April 2018 to July 2022 were selected. According to the FeNO level at the first visit, the subjects were divided into different high- and low-FeNO groups according to the American Thoracic Society (ATS) guidelines and the Chinese multicenter study recommendations. The consistency of the two grouping methods and the differences between the high- and low-FeNO groups were compared after standardized treatment. The grouping method that was the most suitable for children in the cross group was discussed.

Results

(i) There was fair consistency between the Chinese multicenter study recommendations and the ATS guidelines regarding the classification of high- and low-FeNO groups (Kappa = 0.338). (ii) Repeated-measures ANOVA showed that the level of improvement in FVC%, FEV1%, FEF25%, FEF50%, and FeNO in the American high- and low-FeNO groups differed with the duration of therapy (P < 0.05), however, there was no significant difference between the Chinese groups. (iii) FEV1% and FeNO improved more after treatment in the fixed high-FeNO group than in the cross group (P < 0.05).

Conclusion

The Chinese multicenter study on the normal range of FeNO in children in China has a limited role in evaluating standardized asthma treatment efficacy in 6- to 12-year-old children. The ATS guidelines are currently recommended for clinical assessment of asthma treatment efficacy.

Fractional Exhaled Nitric Oxide (FeNO) in Patients with Stable Chronic Obstructive Pulmonary Disease: Short-Term Variability and Potential Clinical Implications

BACKGROUND

The use of fractional exhaled nitric oxide (FeNO) has been proposed for identifying and monitoring eosinophilic airway inflammation in chronic obstructive pulmonary disease (COPD). To explore the clinical utility of FeNO in COPD, we aimed to assess its short-term variability in a clinically stable COPD cohort.

METHODS

Consecutive COPD patients, formerly smokers, underwent FeNO assessment at the baseline and six time-points through serial sampling spaced 3 days apart.

RESULTS

A total of 41 patients (mean age 72.9, 87.8% males) showed a median baseline value of FeNO of 11.7 (8.0-16.8) ppb. A weak linear relationship was documented between baseline FeNO values and both eosinophil counts (r = 0.341, p = 0.029) and the percentage of eosinophils (r = 0.331, p = 0.034), confirmed in multiple linear regressions after adjusting for steroid use. The overall individual variability of FeNO between time-points was 3.90 (2.53-7.29) ppb, with no significant difference in the distribution of FeNO values measured at different time-points (p = 0.204). A total of 28 (68.3%) patients exhibited FeNO always below the 25 ppb cut-off at all determinations, while the remining 13 (31.7%) had at least one value above the established limit. Interestingly, none of these 13 participants had FeNO stably above 25 ppb, all showing at least one normal value during serial sampling. Compared to these patients with more fluctuating values, the 28 with stably normal FeNO only exhibited a significantly higher body weight (80.0 ± 18.2 kg vs. 69.0 ± 8.8 kg, p = 0.013) and body mass index (29.7 ± 6.5 kg/m2 vs. 25.9 ± 3.7 kg/m2, p = 0.026), confirmed in multiple logistic regressions after adjusting for major potential confounders.

CONCLUSIONS

A certain degree of FeNO variability, apparently unrelated to eosinophil counts but somehow influenced by body weight, must be considered in COPD patients. Further studies are needed to clarify whether this biomarker may be effectively used to plan more personalized pharmacological and rehabilitation strategies in this clinical setting.

Association between exposure to a mixture of metals, parabens, and phthalates and fractional exhaled nitric oxide: A population-based study in US adults

The effects of environmental endocrine-disrupting chemicals (EDCs) (e.g., phthalates) on fractional exhaled nitric oxide (FeNO) in children have received much attention. However, few studies evaluated this relationship in adults, and the previous studies have considered only a unitary exposure or a set of similar exposures instead of mixed exposures, which contain complicated interactions. We aimed to evaluate simultaneously the relationship between three types of EDCs (six phthalate metabolites and two parabens in urine, two heavy metals in blood) and FeNO (as a continuous variable) in adults. Data of adults aged ≥20 years from the National Health and Nutrition Examination Survey (NHANES, 2007-2012) were collected and analyzed. The generalized linear (GLM) regression model was used to explore the association of chemicals with FeNO. The combined effect of 10 chemicals on the overall association with FeNO was evaluated by the weighted quantile sum regression (WQS) model. In addition, The Bayesian kernel machine regression (BKMR) model was explored to investigate the interaction and joint effects of multiple chemicals with FeNO. Of the 3296 study participants ultimately included, among the GLMs, we found that mercury (Hg) (β = 0.84, 95%CI:0.32-1.36, FDR = 0.01) and methyl paraben (MPB) (β = 0.47, 95%CI:0.16-0.78, FDR = 0.015) were positively correlated with FeNO. In the WQS model, the combined effect of chemicals almost had a significantly positive association with FeNO and the top three contributors to the WQS index were Hg (40.2%), MECPP (22.1%), and MPB (19.3%). BKMR analysis showed that there may be interactions between MPB and Hg, Mono (carboxyoctyl) phthalate (MCOP) and Hg and the overall effect of the mixture showed a positive correlation with FeNO. In conclusion, our study strengthens the credibility of the view that EDCs can affect respiratory health. In the future, we should be particularly careful with products containing Hg, MECPP, MPB, and MEHP for the prevention of respiratory diseases.

The Effect of Obesity on Fractional Exhaled Nitric Oxide in School-Aged Children

Background: Fractional exhaled nitric oxide (FeNO) is recognized as a biomarker of eosinophilic inflammation. Current literature shows evidence that FeNO is influenced by many factors. Obesity is a chronic inflammatory state. In this study, we considered obesity as a potential factor that influences FeNO levels. The aim of the study was to analyze the association between body mass index (BMI, body mass (kg)/height (m)2) and FeNO levels in a young group of children. Methods: The participants in the study were 506 school-aged children who were randomly selected from primary schools located in Silesian Voivodship (Poland). The modified version of the Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was used to assess the respiratory system status of children. FeNO was measured in 447 children according to European Respiratory Society and America Thoracic Society (ERS/ATS) recommendations. Body mass and height were measured by a medical body composition analyzer. BMI was defined and interpreted with Palczewska’s percentile charts. Results: In the study group there were 49.9% (n = 223) boys and 50.1% (n = 224) girls. The frequency of normal BMI was 76.8% (n = 172), overweight 13.7% (n = 31) and obesity 9.4% (n = 21) in girls, while the normal BMI was found in 71.3% (n = 159), overweight 11.6% (n = 26) and obesity 17% (n = 38) in boys, the differences not statistically significant (p = 0.05). The mean FeNO value in children with obesity was 16.1 ± 12.5 ppb, in children with normal BMI 15.8 ± 15.5 ppb and the lowest FeNO values were in children with overweight 15.3 ± 13.0 ppb; p = 0.9. The FeNO values after adjusting for age, sex, BMI and symptoms from respiratory system were depended on age and respiratory symptoms only. Conclusions: In 6–9 year old school children, FeNO levels are associated with age and health in relation to the respiratory system. The BMI should not be included when considering reference values for FeNO.

Th1/Th2 cytokines profile in overweight/obese young adults and their correlation with airways inflammation

Objectives

Methods

Results

Conclusion

Association between exposure to polyfluoroalkyl chemicals and increased fractional exhaled nitric oxide in adults

BACKGROUND

Perfluoroalkyl chemicals (PFCs) are widely detected in the environment and human body, and they have been linked to asthma and a number of respiratory responses in children and mice. However, no previous studies have investigated the association between exposure to PFCs and airway inflammation in adults.

OBJECTIVES

To evaluate the associations between serum PFCs and fractional exhaled nitric oxide (FeNO), a biomarker of airway inflammation, in adults.

METHODS

A cross-sectional study of 3630 adults aged 20-79 years who participated in the National Health and Nutrition Examination Survey (NHANES, 2007-2012) was conducted. Serum concentrations of five major PFCs were measured using SPE-HPLC-TIS-MS/MS method, including perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and perfluorodecanoic acid (PFDE). The detection rates of them were all >85%. Weighted multivariable linear regression and Bayesian kernel machine regression (BKMR) analyses were applied to examine the associations between serum PFCs and FeNO.

RESULTS

After adjusted for potential confounding factors, linear regression analyses found that compared with their lowest tertiles, highest tertiles of PFOS, PFDE and PFOA were significantly associated with 5.02% (95% CI: 1.40%, 8.77%), 3.77% (95% CI: 0.30%, 7.36%) and 6.34% (95% CI: 2.81%, 10.01%) increases in FeNO, respectively. The second tertile of PFNA was significantly correlated with a 4.79% (95% CI: 1.41%, 8.29%) increase in FeNO compared with the lowest tertile. In the BKMR analysis, the mixture effect of PFCs on FeNO increased significantly when the PFC levels were at or above the 60th percentiles compared to those at their medians. PFOS and PFOA displayed significant positive single-exposure effects on FeNO when all the other PFCs are set at a particular threshold.

CONCLUSIONS

This study provided preliminary evidence that serum PFCs were positively associated with increased FeNO in adults.

Causal Effects of Body Mass Index on Airflow Obstruction and Forced Mid-Expiratory Flow: A Mendelian Randomization Study Taking Interactions and Age-Specific Instruments Into Consideration Toward a Life Course Perspective

Obesity has complex links to respiratory health. Mendelian randomization (MR) enables assessment of causality of body mass index (BMI) effects on airflow obstruction and mid-expiratory flow. In the adult SAPALDIA cohort, recruiting 9,651 population-representative samples aged 18–60 years at baseline (female 51%), BMI and the ratio of forced expiratory volume in 1 second (FEV₁) to forced vital capacity (FVC) as well as forced mid-expiratory flow (FEF25–75%) were measured three times over 20 follow-up years. The causal effects of BMI in childhood and adulthood on FEV1/FVC and FEF25–75% were assessed in predictive (BMI averaged over 1st and 2nd, lung function (LF) averaged over 2nd and 3rd follow-up; N = 2,850) and long-term cross-sectional models (BMI and LF averaged over all follow-ups; N = 2,728) by Mendelian Randomization analyses with the use of weighted BMI allele score as an instrument variable and two-stage least squares (2SLS) method. Three different BMI allele scores were applied to specifically capture the part of BMI in adulthood that likely reflects tracking of genetically determined BMI in childhood. The main causal effects were derived from models containing BMI (instrumented by BMI genetic score), age, sex, height, and packyears smoked as covariates. BMI interactions were instrumented by the product of the instrument (BMI genetic score) and the relevant concomitant variable. Causal effects of BMI on FEV1/FVC and FEF25–75% were observed in both the predictive and long-term cross-sectional models. The causal BMI- LF effects were negative and attenuated with increasing age, and stronger if instrumented by gene scores associated with childhood BMI. This non-standard MR approach interrogating causal effects of multiplicative interaction suggests that the genetically rooted part of BMI patterns in childhood may be of particular relevance for the level of small airway function and airflow obstruction later in life. The methodological relevance of the results is first to point to the importance of a life course perspective in studies on the etiological role of BMI in respiratory health, and second to point out novel methodological aspects to be considered in future MR studies on the causal effects of obesity related phenotypes.

The Effect of Adiposity Markers on Fractional Exhaled Nitric Oxide (FeNO) and Pulmonary Function Measurements

Background

The effect of increasing body weight on pulmonary function and the fractional exhaled nitric oxide (FeNO) remains controversial and the role of different body compositions in the relationship between obesity with pulmonary function and FeNO is still unrevealed. Thus, we aim to determine the effect of overweight/obesity on lung function and FeNO, focusing on the relationship with different body compositions.

Methods

Eighty-two non-smoker students (20 ± 1.9 years) were divided into two groups: 38 subjects with normal weight (BMI = 18.5–24.99) and 44 overweight/obese subjects (BMI ≥ 25). Spirometric parameters and FeNO were measured and compared between groups and were correlated with different adiposity markers.

Results

FeNO measurements were elevated in the overweight/obese group [median (IQR) 19.5 (13)] in comparison to the normal weight group [11 (10), p value = 0.017]. A positive correlation was found between FeNO measurements and body mass index (BMI), waist circumference, hip circumference, waist-hip ratio, and visceral fat percentage (all p values < 0.01). The absolute values of forced vital capacity (FVC) forced expiratory volume in the first second (FEV₁), peak expiratory flow (PEF), forced expiratory flow during mid-expiration (FEF_25–75%), and FEV₁/FVC ratio showed no significant differences between groups. However, the percentage of the predicted values of FEV₁ and FVC was significantly higher and the value of percentage predicted FEF_25–75% was reduced significantly in the overweight/obese subjects.

Conclusion

Increase in BMI could significantly increase airway inflammation as measured by FeNO, as well as on distal airway function as determined by the percentage predicted values of FEF_25–75%. A significant correlation was also identified between visceral fat and FeNO measurement.

Obesity, sedentary lifestyle, and exhaled nitric oxide in an early adolescent cohort

Fractional exhaled nitric oxide (FeNO) is a marker of airway inflammation that is well-characterized in allergic disease states. However, FeNO is also involved in nonallergic inflammatory and pulmonary vascular mechanisms or responses to environmental stimuli. We sought to determine the extent to which obesity or sedentary lifestyle is associated with FeNO in adolescents not selected on the basis of allergic disease. In Project Viva, a prebirth cohort study, we measured body mass index (BMI), skinfold thicknesses, waist circumference, body fat, hours watching television, hours of physical activity, and heart rate after exercise among 929 adolescents (median age, 12.9). We measured FeNO twice and averaged these as a continuous, log-transformed outcome. We performed linear regression models, adjusted for child age, sex, height, and race/ethnicity, maternal education and smoking during pregnancy, household income and smoking, and neighbourhood characteristics. In secondary analysis, we additionally adjusted for asthma. More than 2 hours spent watching TV was associated with 10% lower FeNO (95% confidence interval [CI]: -20, 0%). Higher body fat percentage was also associated with lower FeNO. After additional adjustment for asthma, teens who are underweight (BMI <5th %tile, 3%) had 22% lower FeNO (95%CI: -40, 2%) and teens who are overweight (BMI ≥85th %ile, 28%) had 13% lower FeNO (95%CI: -23, -2%). Each of these associations of lifestyle and body weight with lower FeNO were greater in magnitude after adjusting for asthma. In summary, sedentary lifestyle, high and low BMI were all associated with lower FeNO in this adolescent cohort.

Exhaled nitric oxide in pediatric patients with respiratory disease

Measurement of nitric oxide (NO) levels in exhaled air from the upper and lower airways is currently used as a non-invasive marker of inflammation in respiratory diseases. Assessment of NO exhaled from the lower air respiratory tract is considered to be a quick method for confirmation and control of asthma in patients as well as an estimation of treatment efficiency. The main aim of this study was to determine differences between levels of exhaled nitric oxide (fractional exhaled NO; FeNO) in patients with respiratory disease as measured by an electrochemical analyzer. Measurements were taken in 352 pediatric patients aged 4-17 with cystic fibrosis (CF) (n = 43), asthma (n = 69), allergic rhinitis (AR) (n = 70), asthma and AR (n = 128) and non-diseased children (n = 42) recruited from the Allergology Outpatient Department, Provincial Hospital No 2, Rzeszów. The second objective of this study was to assess any correlations between FeNO and clinical parameters of patients. The level of FeNO in patients with CF was normal when compared with control subjects (10.8 ± 2.9 versus 11.4 ± 6 ppb). We found significantly higher FeNO in patients with asthma (26.6 ± 15.3 ppb, p < 0.001), AR (18.4 ± 9.6 ppb, p < 0.01) as well as in patients with both asthma and AR (43.3 ± 31.1 ppb, p < 0.001) when compared to healthy children. Statistical analysis revealed a positive correlation between FeNO and age, height and weight of control subjects, and height in children with AR. FeNO was independent of sex, BMI, spirometry and blood results as well as the type of residence in control children and subjects with CF, asthma, AR and combined asthma and AR. In conclusion, we found normal levels of FeNO in children with CF and elevated levels in patients with asthma, AR and combined asthma and AR as compared to control subjects. Due to conflicting data, there is still a need for additional research, especially related to regarding factors that affect FeNO levels in respiratory disease.

How Maternal BMI Modifies the Impact of Personalized Asthma Management in Pregnancy

BACKGROUND

Maternal asthma is associated with perinatal complications and respiratory illness in offspring. Obesity increases asthma exacerbation risk in pregnancy and risk of wheeze in offspring.

OBJECTIVES

In this secondary analysis of a randomized controlled trial, we investigated the influence of maternal body mass index, gestational weight gain (GWG), and fractional exhaled nitric oxide (F_ENO)-based management on asthma exacerbations in pregnancy and offspring wheeze.

METHODS

A total of 220 women were randomized to asthma treatment adjustment according to symptoms (control group), or F_ENO and symptoms (F_ENO group). Exacerbations were recorded prospectively. Height and weight were measured at baseline, and in late pregnancy. GWG was categorized according to Institute of Medicine guidelines. A validated parent-completed questionnaire assessed infant wheeze-related outcomes.

RESULTS

F_ENO-based management was associated with a significantly lower incidence rate ratio for maternal exacerbations in nonobese mothers (0.52, 95% confidence interval [CI], 0.31-0.88, P = .015, n = 129), and women with GWG within recommendations (0.35, 95% CI, 0.12-0.96, P = .042, n = 43), but not for obese mothers (0.59, 95% CI, 0.32-1.08, P = .089, n = 88), or women with excess GWG (0.58, 95% CI, 0.32-1.04, P = .07, n = 104). Recurrent bronchiolitis occurred in 5.3% (n = 1) of infants born to non-overweight mothers, 16.7% (n = 3) of infants of overweight mothers, and 21.7% (n = 5) of infants of obese mothers in the control group. In the F_ENO group, 2 infants of obese mothers had recurrent bronchiolitis (7.1%, P = .031).

CONCLUSIONS

The benefits of F_ENO-based management are attenuated among obese mothers and those with excess GWG, indicating the importance of weight management in contributing to improved asthma management in pregnancy.

Is asthma in the elderly different? Functional and clinical characteristics of asthma in individuals aged 65 years and older

BACKGROUND

The prevalence of chronic diseases in the elderly (> 65 years), including asthma, is growing, yet information available on asthma in this population is scarce.Our objective is to determine the differential clinical and functional characteristics of the population > 65 years old with asthma included in the Integrated Research Programs of Asthma Databank of the Spanish Society of Pneumology and Thoracic Surgery (www.bancodatosasma.com).

METHODS

Retrospective comparative descriptive study of demographic, clinical and functional variables for 1713 patients with asthma categorized into 3 age groups as follows: adults aged < 65 years (A), younger elderly aged 65-74 years (B) and older elderly aged ≥75 years (C).

RESULTS

Predominant features of elderly patients with asthma (N = 471) were the female sex, fewer smokers, greater obesity, poorer lung function, and lower values of nitric oxide in exhaled air (p < 0.01). The most frequently associated comorbidity was gastroesophageal reflux. The highest doses of inhaled corticosteroids were by group A (60.8%). For the sample overall, 23.2% (N = 398) were being treated with omalizumab and 8.2% (N = 140) were corticosteroid-dependent (10.6% in group B). The highest percentage of patients receiving antileukotriene agents was in group B (42.9%).

CONCLUSIONS

Asthma in adults aged> 65 is more severe and associated with greater comorbidity, which would indicate the need for a more integrated and multidimensional approach to asthma treatment for these patients.

Chronic cough and obesity

With respective prevalence of 13% and 9.6%, obesity and chronic cough are two common conditions worldwide. The crucial role of obesity has been highlighted in the development and progression of many respiratory diseases. According to the results of epidemiological studies, obesity, particularly abdominal obesity, may also be associated with chronic cough (CC). CC seems to be more severe in obese patients compared to normal-weight subjects. The management of CC may differ slightly in obese patients compared to non-obese patients. Indeed, asthma and reflux diseases, which are considered key factors in the onset of CC, are characterised by more severe symptoms in obese patients. Asthma is associated with a resistance to usual treatments in obese patients but no data are available on the effect of inhaled therapies in obese subjects with cough variant asthma. Other emergent causes of CC have been reported in obese patients. Obstructive sleep apnoea and diabetes may also be involved in the development of CC and should be taken into account in obese patients with CC. The beneficial effect of weight loss on chronic cough has been suggested.

Psoriasis and Respiratory Comorbidities: The Added Value of Fraction of Exhaled Nitric Oxide as a New Method to Detect, Evaluate, and Monitor Psoriatic Systemic Involvement and Therapeutic Efficacy

Psoriasis is a chronic inflammatory systemic disease characterized by a wide range of comorbidities. Respiratory comorbidities are currently poorly characterized and with discordant results. The systemic state of inflammation caused by psoriasis acts de novo on respiratory tissues and amplifies preexisting inflammation from asthma or chronic obstructive pulmonary disease. Because the lungs act as a gas exchanger between the internal and external environment, the impact of chronic psoriasis inflammation may be easily assessed through the analysis of exhaled breath. The fraction of exhaled nitric oxide test (FeNO) is a potential noninvasive solution that can provide quantitative and qualitative indices of respiratory airway inflammation. FeNO is routinely used to screen and manage asthmatic patients. Recent pilot studies contain encouraging data that underscore its possible use with systemic inflammatory nonpulmonary diseases, such as psoriasis. FeNO may therefore be a useful tool to evaluate underestimated airway inflammation and at the same time globally evaluate the impact of systemically antipsoriatic therapies.

Baseline Features of the Severe Asthma Research Program (SARP III) Cohort: Differences with Age

BACKGROUND

The effect of age on asthma severity is poorly understood.

OBJECTIVES

The objective of this study was to compare the baseline features of severe and nonsevere asthma in the Severe Asthma Research Program (SARP) III cohort, and examine in cross section the effects of age on those features.

METHODS

SARP III is a National Institutes of Health/National Heart Lung Blood Institute multisite 3-year cohort study conducted to investigate mechanisms of severe asthma. The sample included 188 children (111 severe, 77 nonsevere) and 526 adults (313 severe, 213 nonsevere) characterized for demographic features, symptoms, health care utilization, lung function, and inflammatory markers compared by age and severity.

RESULTS

Compared with children with nonsevere asthma, children with severe asthma had more symptoms and more historical exacerbations, but no difference in body weight, post-bronchodilator lung function, or inflammatory markers. After childhood, and increasing with age, the cohort had a higher proportion of women, less allergen sensitization, and overall fewer blood eosinophils. Enrollment of participants with severe asthma was highest in middle-aged adults, who were older, more obese, with greater airflow limitation and higher blood eosinophils, but less allergen sensitization than adults with nonsevere asthma.

CONCLUSIONS

The phenotypic features of asthma differ by severity and with advancing age. With advancing age, patients with severe asthma are more obese, have greater airflow limitation, less allergen sensitization, and variable type 2 inflammation. Novel mechanisms besides type 2 inflammatory pathways may inform the severe asthma phenotype with advancing age.

Reference values of fractional excretion of exhaled nitric oxide among non-smokers and current smokers

BACKGROUND

Fractional exhaled nitric oxide (FENO) is used to assess of airway inflammation; diagnose asthma and monitor adherence to advised therapy. Reliable and accurate reference values for FENO are needed for both non-smoking and current smoking adults in the clinical setting. The present study was performed to establish reference adult FENO values among never-smokers, former smokers and current smokers.

METHODS

FENO was measured in 5265 subjects aged 25-75 years in a general-population study, using a chemiluminescence (Niox ™) analyser according to the guidelines of the American Thoracic Society and the European Respiratory Society. Atopy was based on the presence of immunoglobulin E (IgE) antibodies to common inhalant allergens (measured using Phadiatop® test). Spirometry without bronchodilation was performed and forced vital capacity (FVC), forced expired volume in 1 s (FEV1) and the ratio of FEV1 to FVC values were obtained. After excluding subjects with asthma, chronic bronchitis, spirometric airway obstruction and current cold, 3378 subjects remained. Equations for predictions of FENO values were modelled using nonparametric regression models.

RESULTS

FENO levels were similar in never-smokers and former smokers, and these two groups were therefore merged into a group termed "non-smokers". Reference equations, including the 5th and 95th percentiles, were generated for female and male non-smokers, based on age, height and atopy. Regression models for current smokers were unstable. Hence, the proposed reference values for current smokers are based on the univariate distribution of FENO and fixed cut-off limits.

CONCLUSIONS

Reference values for FENO among respiratory healthy non-smokers should be outlined stratified for gender using individual reference values. For current smokers separate cut-off limits are proposed.

Nasal Nitric Oxide in Healthy Adults – Reference Values and Affecting Factors

Nitric oxide (NO) is an important endogenous mediator with significant role in the respiratory system. Many endogenous and exogenous factors influence the synthesis of NO and its level is significantly changed during the inflammation. Analysis of nasal nitric oxide (nNO) is not validated so far as the diagnostic method. There is a lack of reference values with possible identification of factors modulating the nNO levels. In healthy adult volunteers (n=141) we studied nasal NO values by NIOX MINO® (Aerocrine, Sweden) according to the recommendations of the ATS & ERS. Gender, age, height, body weight, waist-to-hip ratio, FEV1/FVC, PEF and numbers of leukocytes, eosinophils, basophils and monocytes were studied as potential variables influencing the levels of nNO. The complexity of the results allowed us to create a homogenous group for nasal NO monitoring and these data can be used further as the reference data for given variables. Because of significant correlation between nNO and exhaled NO, our results support the “one airway – one disease” concept. Reference values of nasal NO and emphasis of the individual parameters of tested young healthy population may serve as a starting point in the non-invasive monitoring of the upper airway inflammation.

Overweight in childhood and adolescence: Does it lead to airway hyperresponsiveness in adulthood?

BACKGROUND

Obesity is increasing worldwide among children and adolescents, and has been associated with an increased incidence of asthma. However, the mechanisms underlying this association are incompletely understood.

OBJECTIVE

In this cohort study we aimed to investigate whether being overweight in childhood and adolescence is associated with an increased risk of airway hyperresponsiveness (AHR), a hallmark of asthma, in early adulthood.

METHODS

Of 527 subjects from a random population sample of children and adolescents (7-17 years) examined at baseline, a total of 184 subjects completed the follow-up visit 20 years later and were included in the present analysis. Both visits included assessment of height and weight, case history and spirometry. At both visits, bronchial provocation tests were performed using either histamine (baseline) or methacholine (follow-up). In addition, fractional exhaled nitric oxide (FeNO) was measured at follow-up.

RESULTS

No significant difference in the prevalence of AHR at follow-up was found between subjects who were overweight or obese at baseline visit (n = 26) (pediatric definition, body mass index ≥ 85%percentile) and normal weight subjects (n = 158) (positive bronchial provocation tests: 15.4% vs. 22.2%, respectively, p = 0.35). Likewise, follow-up FeNO levels did not differ significantly between subjects who were lean and those who were overweight or obese at baseline (geometric mean (95% confidence interval [CI]) 15.1 (13.7, 16.6) parts per billion (ppb) versus 13.0 (10.6, 15.9) ppb, p = 0.23).

CONCLUSION

In children and adolescents, being obese or overweight seems not to be associated with an increased risk of AHR or increased FeNO levels in early adulthood.

Association between fractional exhaled nitric oxide and clinical characteristics and outcomes in patients with subacute cough

OBJECTIVES

To investigate the relationships between fractional exhaled nitric oxide (FENO) and clinical characteristics and outcomes in patients with subacute cough.

METHODS

Patients with subacute cough (n = 189) after upper respiratory tract infection were enrolled in this single-center prospective study, and were divided into low-FENO (<25 ppb) and high-FENO groups (≥25 ppb). Empirical therapies (without inhaled or systemic corticosteroids) were prescribed based on clinical experience and follow-up until the disease course reached 8 weeks. FENO values, cough symptom scores (CSS), and Leicester Cough Questionnaire (LCQ) scores were obtained, analyzed, and compared between two groups of patients.

RESULTS

The low-FENO and high-FENO groups comprised 136 and 53 patients, respectively. The multiple regression analysis showed that blood eosinophil count and gender were independent factors for elevated FENO (β = 1.38, 0.25, respectively). LCQ scores, total CSS, and daytime CSS were comparable between the low-FENO and high-FENO groups. The nighttime CSS of the high-FENO group were significantly higher than that of the low-FENO group (P = .03). The CSS and LCQ score were improved in both groups but were comparable between groups after 10 days treatment.

CONCLUSIONS

Patients with subacute cough and high-FENO levels have more severe nocturnal cough than those of patients with low-FENO levels. However, FENO levels do not appear to correlate with the clinical outcomes or treatment response. The significance of FENO in the management of subacute cough needs to be further evaluated, at least in the current empirical treatment without corticosteroids.